Hobby Circuits

Various hobby circuits that we can do at out workbench.

Mobile Phone Detector Circuit

Mobile Phone Detector Circuit

This is a very interesting hobby project which can detect active mobile phone or GSM communication in its proximity. Active mobile phone means there is some live communication is going on like calls, sms sending or receiving etc. This circuit can be used to prevent unauthorized use of mobile phones in examination halls, conference rooms etc. As you already know, today’s mobile phones (2G, 2.5G, 3G, 4G, LTE) are operating in electromagnetic signals ranges from 700MHz to 3500MHz. Each countries [...]

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LED Chaser using 4017 and 555 Timer - PCB

LED Chaser using 4017 Counter and 555 Timer

Introduction A simple LED chaser hobby circuit can be made using 555 timer and CD4017 counter IC. You can use this circuit for decorative purposes. By modifying the circuit in a proper way, you can even use this to control lights working on AC mains. Components Required CD4017 Counter IC – 1 555 Timer IC – 1 LED – 11 680Ω Resistor – 11 10KΩ Resistor – 1 10KΩ Variable Resistor – 1 10μF Capacitor – 1 0.01μF Capacitor – 1 9V Battery / Power Supply – 1 Circuit Diagram LED Chaser using [...]

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Rain Alarm using 555 Timer - PCB

Rain Alarm using 555 Timer

Here is a simple and interesting hobby circuit that can be made using the popular 555 timer IC. As you might already know, a 555 Timer can be easily wired as Astable, Monostable or Bistable multivibrator. This circuit can be used as rain sensor, water overflow sensor or as a water level sensor. This circuit make use the principle that normal water can conduct some amount of electricity (PURE water is not a good conductor of electricity but water seen [...]

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ANL on breadboard

Automatic Night Lamp using LDR

Automatic night lamp as the name suggests is for turning ON and OFF the lamp automatically without the need of human interventions. It senses the light intensity from surroundings and find whether its day or night. And it automatically turns ON when the surrounding is dark and it turns OFF when it receives light from surroundings. A sensor called LDR is used to detect the light intensity. This project finds wide outdoor applications in streets, gardens and public places [...]

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12V Capacitor Dropper Power Supply Output

Transformerless Capacitor Dropper Power Supply

I already posted about transformerless power supplies in the article, Transformerless DC Power Supply. Here we will see how to design a capacitor dropper power supply. Capacitor power supplies are simple, low cost and light weight solution for providing dc supplies to circuits which require low currents. It is low cost and light weight since there is no bulky transformers. Circuit Diagram Transformerless Capacitor Power Supply 12V 40mA The 200mA fuse will protect the circuit from mains during shot circuit or component failures. The [...]

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Simple Electronic Piano using 555 Timer

A simple electronic toy piano can be easily constructed using the popular 555 timer IC. 555 Timer can be easily wired as Astable, Monostable or Bistable multivibrator. We all know that Sound is a Mechanical Wave as it is produced by to and fro movement of particles of the medium. Displacement of particles are in the same direction as propagation of sound waves, so sound is a Longitudinal Wave. The to and fro motion of particles in the medium creates [...]

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IC UM3561 Siren Generator

Siren Generator using IC UM3561

IC UM3561 is a CMOS LSI IC commonly used in alarm and toy applications. It is able to generate Police Siren, Ambulance Siren, Fire Engine Siren and Machine Gun Sound just by changing simple connections. It is a low cost and low power IC which can work down to 2.4V. We need only a few additional components as this Integrate Circuits has built in oscillator and selector circuits.  About IC UM3561 IC UM3561 – Block Diagram Basic blocks of IC UM3561 are [...]

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UM66 Music Circuit on Breadboard

UM66 Melody Generator – First Step for Electronics Hobbyists

UM66 UM66 is a melody generating IC commonly used in calling bell, phone, toys, musical bell in doors, home security alarm systems, burglar alarms etc. It is a three pin IC looks like a transistor. Its first pin is ground, second is VCC and the third is the melody output. Supply voltage that can be given to the IC is in the range of 1.5V- 4.5V. These are CMOS ICs and have very small power consumption. Melody generator will reset when [...]

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